This invention relates to mass spectrometers and more particularly to a mass spectrometer which has multiple collectors for simultaneously measuring the intensity of beams of ions of different mass.
Multiple collectors in mass spectrometers permit the simultaneous measurement of multiple ion beams. They have the advantage of collecting a greater proportion of the total available ion current during a given period of time with improved precision and reduced analyses times. The effects of fluctuations of ion beams with respect to time are reduced and other variables such as amplifier decay constant effects are eliminated.
Multiple collector mass spectrometers are particularly useful in geochronology wherein the intensity of certain radiogenic isotopes is measured and normalized on the assumption that certain ratios are constant. This technique is described in NATURAL RADIOGENIC ISOTOPES: TRACES OF GEOLOGICAL PROCESSES, A. W. Hofman Max-Planck-Institut fur Chemie 6500 Mainz, F.R. Germany, SPECTRA, Vol. 8, No. 4.
Typically, the isotopes of strontium are measured. However, the measurement of other isotopes is desirable. Because these isotopes have different mass, the positioning of the collector plates is changed to measure different isotope ratios. State of the art mass spectrometers have collectors with adjustable separations. Such mass spectrometers are described in MULTICOLLECTION IN THERMAL IONISATION MASS SPECTROMETRY by Patrick J. Turner, VG Isotopes Limited, Winford, Cheshire CW7 3BX, England and in publication 02.481 JC January 1982, a Newsletter from VG Isotopes Limited.
It is an object of the present invention to improve the resolving accuracy and speed of measurement of mass spectrometers which have multiple collectors.